1. Field of the Invention
The invention relates to a gear constructional unit in particular with an essentially cylindrical interior space and bar form guide elements for mounting gear elements.
2. Description of the Related Art
Gear constructional units are known in a large number of executions. These can be executed as
a) a mechanical gear component
b) a hydrodynamic-mechanical compound gear component.
Hydrodynamic-mechanical compound gear components are known, for example, from the following publications:
Buksch, M: ZF five-gear automatic gears for passenger cars, VDI report 878 (1991)
Mitescko, G: Four-gear planetary gears for passenger cars with the hydrodynamic torque converter in the power branch, Automobilindustrie (1995) 5, pages 597-602
Klement, W.: The development of the DIWA gears, Verkehr und Technik (1997) 7, pages 301-303
Gear components which have either only purely mechanical transmission components or else consist of a combination of a hydrodynamic converter or of a hydrodynamic coupling with a downstream mechanical gear set, have as a rule a housing which in respect to its inner contour is adapted to the shape of the individual gear elements and to their connection to the housing and they have, as a rule, interior insets which undesirably reduce the inside diameter. For example, one known gear uses a threading of the gear elements onto six rods which are allocated to the interior space of the gear circumferentially at uniform intervals. This makes possible, to be sure, a very simple assembling of the components or gear elements, but the arrangement of the six bars in circumferential direction with constant spacing between two bars, as well as the number of these rods considerably reduces the inside diameter of the gear system, since the upper bars in installation position determine the structural height and therewith also the possible usable planetary diameter.
Underlying the invention, therefore, is the problem of creating a possibility for the formation of gear components, especially gear housings, with which in firmly prescribed installation as high as possible torques can be transmitted. In detail, there, emphasis is to be given to a reduction of the constructive and above all of the manufacturing technical expenditure as well as a minimizing of the required number of components.
According to the invention the gear component, which comprises a gear housing and has a substantially cylindrical interior space, has at least two bar-form elements for the tying-on of gear elements in radial direction with respect to the gear axis, or in peripheral direction. The bar-form guide elements extend there essentially over a range in which there are arranged the gear elements provided for the tying-on. The bar-form guide elements are assigned to the cylindrical interior space and are arranged outside of this, in which the allocation occurs in such manner that the bar-form guide elements are provided outside of a zone which, as viewed in installation position of the gear, corresponds to the greatest dimension of the interior space in elevation direction of the gear component.
This means that none of the guide elements is arranged in installation position above the greatest dimension of the interior space in elevation direction, in the gear housing, but rather they are in the zones formerly more intensive in material for the gear housing, with an essentially quadrangular gear external contour with cylindrical interior space.
Under a further aspect of the invention there occurs there an arrangement of the bar-form guide elements with respect to the cylindrical interior space in a zone which is bounded by the installation position
Under a further aspect of the invention there occurs there an arrangement of the bar-form guide elements with respect to the cylindrical interior space in a zone which is bounded by the minimal and maximal dimensions of the cylindrical interior space. This means that there does not occur an arrangement directly above the greatest dimension in elevation direction, or underneath the lowest dimension of the cylindrical interior space in elevation direction, on the symmetry line of the cylindrical interior space running in elevation direction, as viewed in installation position. This offers the advantage that the housing builds relatively in elevation direction and therefore does justice optimally to the increasingly raised demands on the utilization of the available construction space.
With the solution according to the invention, therefore, the inside diameter or the inside contour of the gear housing can be made noticeably greater with constant installation measures for the gear component. By the guidance of the bar-form guide elements in the recesses which are connected with the cylindrical interior space, the cylindrical interior space can be utilized completely by the gear elements in respect to their radial extent. For example, with execution of the gear elements as a lamellar coupling the surface describable by the cross section surface of the interior space can serve more completely as possibly usable friction surface. Since the bar-form guide elements do not collide with the interior space, the other rotating gear elements, for example planetary wheel sets, can also be laid out in such manner that the entire interior space is completely utilized in radial direction. This leads to the result that because of the diameter increase with the same construction length, a greater torque can be transferred. It is possible to dispense with additional interior insets for the bearing, which reduce the diameter of the interior space. The suspension on the, bar-form guide elements prevents a twisting of the individual gear elements in circumferential direction and, in addition, limits the movability in radial direction with respect to the gear axis.
Compulsorily required are only two bar-form elements; at most four are required and preferably four bar-form guide elements are set in. The arrangement occurs in this case, as viewed in the cross section of the gear housing, in the corners zones, which (cross section) is describable by the section amount between the cylindrical interior space and a theoretically generatable square Qtheoretical with a side dimension greater than or equal to the diameter of the interior space, the theoretically generatable square Qtheoretical and the interior space having identical axes of symmetry. In this case, especially with a rectangular housing with cylindrical interior space, the material-intensive corner zones are used for the reception of the guide elements. The guide elements are guided there in recesses that are connected with the cylindrical interior space. Preferably the arrangement of the guide elements, however, occurs always symmetrically. This offers the advantage that the production expenditure for the gear elements and the gear housing can be minimize, as can also the assembling expenditure, since it is not necessary to take care of how the individual recesses or the passage openings on the gear elements have to be formed for the reception of the guide elements. Furthermore, the hosing base body can be made with the recesses independently of the latter actual installation position.
As gear elements there can be regarded, for example, brake arrangements in the form of lamellar brakes, partitions, actuating elements for braking or coupling devices, for example in the form of cylinders, pistons or cylinder-piston units, lamellae carriers or the like.
The bar-form elements preferably have over their axial extent, a like or constant diameter. This offers the advantage that the assembling can take place independently from the installation direction of the bar-form elements. There is conceivable also, depending on the formation of the total gear component, the use of bar-form elements with different diameter over the axial extent. In this case, however, as a rule, an assembling will occur as a rule from two sides.
By bar-form elements there are meant there guide elements the profile of which is constructed as a solid or hollow profile, or constitutes a combination of the two.
The guide elements, further, depending on the connection, can function as shaft or axles.
It is conceivable, for example, to execute a guide element as a hollow axle which encloses, for example, a shaft for the drive of additional units or an axle.
The cross section of the bar-form guide element is preferably circular. There are conceivable, however, also executions with tetragonal cross section or arbitrary cross section.
In regard to the bearing of the bar-form guide elements the following variants can be used:
a) Bearing on the housing in housing wall projections, for example at the beginning and/or end of the housing
b) Bearing in intermediate walls, which are threaded onto the guide elements
c) Suspended bearing on a wall projection or an intermediate wall, for example on the face sides of the gear, for example over covers
d) Bearing over wall projections (lugs)
The gear component can be constructed as a purely mechanical gear component. In this case each bar-form guide element extends preferably over the entire axial extent of the gear component. In the execution of the gear component as a hydrodynamic-mechanical compound gear, the bar-form guide element is provided with an axial length which corresponds to the axial extent of the mechanical gear part, with respect to the total gear component. It is always required, however, that the axial extent of the guide elements corresponds to the axial extent of the gear element supported on this.
A further possibility for the bearing of the bar-form elements lies in using the housing cover. In the especially preferred forms of execution, however, this possibility is dispensed with, in order to keep the housing cover free from forces, especially axial forces.
In an especially preferred gear component unit devices for the resetting of actuating elements of the lamellar brake- and/or coupling-arrangements are led through the bar-form guide elements. Between the two friction surface-carrying elements which are couplable with one another indirectly by frictional closure, there is provided at least one spring storage arrangement, which is likewise led over the bar-form guide elements and is laid out in such manner that on generation of the frictional closure between the friction surface-carrying elements and the intermediate element the spring storage arrangement is pre-stressable. By friction surface carrying elements there are meant there the elements which are couplable with one another over an intermediate element. In each case a friction surface-carrying element and a friction surface-carrying intermediate element form, on pressing-on a friction surface pair. By friction surface there is meant there the surface or the surface zone which participates in the friction closure. The friction surface there can be a component of the friction surface carrying element or of the intermediate element or it can be allocated to this as a separate element, for example in the form of a covering. The friction surface or the surface zones functioning as friction surface of a friction surface-carrying element or intermediate element can be generated, further, by a coating or surface treatment. The function of friction surface-carrying elements can be taken over there both by the outer as well as also by the inner lamellae. By reason of the effect of the spring storage unit between the individual friction surface-carrying elements, on relaxation of the actuating element in each case there acts an oppositely directed force on the friction surface-carrying elements, so that a rapid separation becomes possible with complete release of the frictional closure. The spring storage arrangements, therefore act indirectly, over a friction surface-carrying element, upon the actuating element. The actuating element itself can be executed, for example, as a piston, which preferably can be acted upon hydraulically or pneumatically. This possibility of arranging the spring storage elements between the friction surface-carrying elements offers the advantage that the dimensions of the friction surface carrying elements in radial direction are no longer dependent on the size of the inner dimensions of the gear housing under consideration for the required construction space for the device, at least for the indirect resetting of the actuating elements. The arrangement of spring storage units between the friction surface-carrying elements connectable with one another over an intermediate element offers the advantage of a space-saving execution of the resetting device, especially of the piston of a cylinder/piston unit in axial direction, which again affects the gear length in use of the brake arrangements in lamellar construction in a gear. In regard to the arrangement of the spring units between the friction surface-carrying elements, a large number of possibilities are conceivable:
a) Arrangement of spring units between each of the two adjacent friction surface-carrying elements;
b) Arrangement of the spring unit in force-flow direction between the friction surface-carrying elements in the zone of the force introduction (in the zone of the in each case outside-lying friction surface-carrying elements with respect to the installation position of the braking arrangement in a gear component);
c) Arrangement of the spring unit between two friction surface-carrying elements adjacent to one another with respect to the axial extent of the braking arrangement in the middle zone of the latter;
d) Arrangement according to b) in combination with c);
e) Arrangement of spring units in correspondence to the possibilities described in a) to d);
f) Combination of e) with the possibilities a) to d).
As spring storage units there are preferably used spring elements which have a characteristic line characteristic with an essentially constant force flow over a certain spring excursion. Preferably, therefore, cup springs are used. The execution of the spring units as a shaft spring ring is likewise thinkable. The actuating arrangements can be executed as cylinder-piston arrangements, which are actable upon hydraulically or pneumatically. In correspondence to the arrangement of the piston for the resetting device over the friction surface-carrying elements, especially lamellae on the piston are active, either in the zone of the piston surface or outside of the piston surface. In regard to the formation of the piston there are distinguished executions with
a) one piston
b) a plurality of pistons.
The appertaining cylinders can be formed there by a cylinder-carrying element or by a plurality of cylinder-carrying elements. This possibility for the piston resetting offers the advantage of a minimal space required in radial as well as in axial direction. In combination with the solution according to the invention there is given the possibility of creating a gear component with the possibility of high torque transmission with the structural height remaining constant, or with a reduced structural height.